Laminated core for motor and method for manufacturing the same

ABSTRACT

Disclosed herein is a laminated core for a motor manufactured by laminating sheets of a plurality of cores. The laminated core is formed by connection of a plurality of split cores, yoke parts of the split cores which are adjacent to each other get in contact with each other so as to form a contact part, and a connection caulking part is formed at the contact part.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a core of a motor. More particularly,the present invention relates to a laminated core for a motor which canmaintain squareness of the laminated core and increase a binding forceof each core, thereby maximizing efficiency of the motor.

2. Background Art

In general, a motor includes a rotor and a stator. The rotor or thestator uses a core made of a conductive metallic material in order toform a necessary magnetic field. Moreover, laminated cores manufacturedby laminating of a plurality of thin steel sheets.

Such a laminated core can show good performance of the motor when eachsheet of the core must be laminated while accurately keeping verticalityand firmly combined with another sheet of the core. In detail, if thecore is laminated without maintaining verticality, namely, if squarenessis not maintained, because an air gap which is a space between the rotorand the stator is not uniform, the rotor shows uneven rotation and isdeteriorated in efficiency.

There are various attempts to combine the sheets of the core. InJapanese Patent Laid-open No. 06-086487, sheets of a core are combinedby being welded perpendicularly in a state where each sheet of the coreis stacked on another. In another way, Japanese Patent Laid-open No.2010-130824 discloses a method for combining sheets of a core bycaulking to pressurize stacked a predetermined position of the stackedsheets of the core by press die.

In a case of laser welding, squareness must be first secured, and then,laser welding is applied. However, caulking is carried out whenever eachsheet of the core is stacked, and hence, caulking is widely used becauseit is effective in keeping squareness. However, the caulking accordingto prior arts has a disadvantage in that it does not secure bondingforce at connected parts of split cores. There is a method toadditionally weld only the connected parts of the split cores or to usea bonding member to the connected parts, but it increases manufacturingexpenses because of additional process.

Therefore, the inventors of the present invention propose a laminatedcore for a motor with a new structure and a method for manufacturing thesame.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve theabove-mentioned problems occurring in the prior arts, and it is anobject of the present invention to provide a laminated core for a motorand a method for manufacturing the same which can secure a combiningforce between sheets of a core and a combining force between split coresadjacent to each other.

It is another object of the present invention to provide a laminatedcore for a motor and a method for manufacturing the same which cansecure squareness of the laminated core so as to enhance performance ofthe motor.

The above and other objects of the present invention will be apparentfrom the following detailed description of the preferred embodiments ofthe invention

To accomplish the above object, according to the present invention,there is provided a laminated core for a motor manufactured bylaminating sheets of a plurality of cores, wherein the laminated core isformed by connection of a plurality of split cores, yoke parts of thesplit cores which are adjacent to each other get in contact with eachother so as to form a contact part, and a connection caulking part isformed at the contact part.

In the present invention, preferably, the contact part has a contactprotrusion formed on one side and a contact groove formed on the otherside.

In the present invention, preferably, the connection caulking partcrosses the contact protrusion and the contact groove.

In the present invention, preferably, the yoke has teeth, and each ofthe teeth has a straight line form on the end flat surface.

In another aspect of the present invention, provided is a method formanufacturing a laminated core for a motor comprising the steps of:stamping a sheet of a core of a straight form to have a form that aplurality of split cores are connected; laminating sheets of the coreperpendicularly; bending the sheets of the core in a round form; andforming a connection caulking part at contact parts of yokes, which areadjacent to each other, of the bended core.

The laminated core for the motor and the method for manufacturing thesame according to the present invention can secure a combining forcebetween sheets of a core and a combining force between split coresadjacent to each other, and secure squareness of the laminated core soas to enhance performance of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be apparent from the following detailed description ofthe preferred embodiments of the invention in conjunction with theaccompanying drawings, in which:

FIG. 1 is a plan view of a laminated core for a motor according to apreferred embodiment of the present invention;

FIG. 2 is a plan view showing a state where the laminated core for themotor is spread in a row;

FIG. 3 is a plan view showing one sheet of the core stamped in order tomanufacture the laminated core for motor according to the preferredembodiment of the present invention;

FIG. 4 is a perspective view showing a state where a plurality of sheetsof the core stamped are laminated to manufacture the laminated core formotor according to the preferred embodiment of the present invention;

FIG. 5 is a perspective view showing a state where a caulking part isformed after the sheets of the core are laminated to manufacture thelaminated core for motor according to the preferred embodiment of thepresent invention;

FIG. 6 is a plan view showing a process to make a round laminated coreby bending the laminated core to manufacture the laminated core formotor according to the preferred embodiment of the present invention;and

FIG. 7 is a plan view showing a state where a connection caulking partis formed on the round laminated core to manufacture the laminated corefor motor according to the preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will be now made in detail to the preferred embodiments of thepresent invention with reference to the attached drawings.

FIG. 1 is a plan view of a laminated core 10 for a motor according to apreferred embodiment of the present invention.

As shown in FIG. 1, the laminated core 10 for the motor according to thepreferred embodiment of the present invention is formed by connecting 12split cores 10 _(a1), 10 _(a2), 10 _(a3), . . . and 10 _(a12) each ofwhich is formed by laminating a plurality of thin metal sheets. Ofcourse, in FIG. 1, 12 split cores form one laminated core 10, but thenumber (n) of the split cores (10 _(an)) is not limited to the above,and at least two split cores can be applied according to sizes of motorsor as occasion demands. Moreover, the laminated core 10 for the motorshown in FIG. 1 is a stator core, but the present invention is notlimited to the stator core and may be applied to a rotor core of a splitcore type in the same way.

Each of the split cores 10 _(a1), 10 _(a2), 10 _(a3), . . . and 10_(a12) shown in FIG. 1 includes an arc-shaped yoke 11 and teeth 12formed in the central direction of a circle to form a circle when thesplit cores 10 _(a1), 10 _(a2), 10 _(a3), . . . and 10 _(a12) are allconnected. In order to increase productivity, preferably, a part wherethe yokes of two split cores get in contact with each other areconnected to each other by a connection part 13. A space part 13 a isformed at a portion which is adjacent to the connection part 13 in thecentral direction of the circle from the connection part 13, and thepart where the yokes of two split cores get in contact with each otheris called a contact part 14. A connection caulking part 15 is formed atthe contact part 14 between the two yokes 11. The connection caulkingpart 15 firmly connects the adjacent split cores so as to help in thatthe laminated core maintain the circular form and to increase thebonding force between the sheets of the laminated core. Furthermore, theconnection caulking part 15 makes each sheet of the core maintain itsaccurate position when the sheets of the core are laminated vertically,and hence, is advantageous in securing squareness of the core.

In order to increase the bonding force of the sheets of the laminatedcore, a caulking part 110 may be formed at a predetermined position, oralternatively, a caulking part 120 may be formed at a predeterminedposition of the teeth 12. Of course, all of the two caulking parts 110and 120 may be formed.

A teeth inner diameter side 12 a is formed at an end side of the innerdiameter of each of the teeth 12. In a case of a general stator core,the teeth inner diameter side 12 a has a circular arc form. However, inthe present invention, the teeth inner diameter side 12 a has not thecircular arc form but a straight line form to reduce a cogging torque.

FIG. 2 is a plan view showing a state where the laminated core for themotor is spread in a row.

Referring to FIG. 2, the 12 split cores 10 _(a1), 10 _(a2), 10 _(a3), .. . and 10 _(a12) which are spread in a row are connected to one anotherby the connection part 13. The position of the connection part 13 islocated at an outer surface part in the opposite direction from thecenter of the circle based on the shape of the circular yoke 11. Theposition is formed at both ends of the yoke of each split core, and iscalled an ear end in the present invention. That is, ear ends of each ofthe split cores 10 _(a1), 10 _(a2), 10 _(a3), . . . and 10 _(a12) areconnected by the connection part 13.

The ear end of one side of the first split core 10 _(a1) has theconnection part 13, but the ear end of the other side does not have theconnection part. In the same way, the ear end of one side of the lastsplit core 10 _(a1) has the connection part 13, but the ear end of theother side does not have the connection part. A connection protrusion 11a and a connection groove 11 b are formed around the two ear ends whichdo not have the connection part, such that the connection protrusion 11a and the connection groove 11 b are connected with each other when thesplit cores are bent in a circular form. After the connection protrusion11 a and the connection groove 11 b are connected with each other, theconnection caulking part 15 is formed at the connected part.

As described above, the space part 13 a is formed at the portion whichis adjacent to the connection part 13 in the central direction of thecircle from the connection part 13. The space part 13 a is formed toprovide a clearance when the split cores are bent and the connectionpart 13 is transformed. Additionally, after the split cores are bent, anadhesive is inserted into the space part 13 a so as to increase thebonding force between the sheets of the core.

A portion which is adjacent to the space part 13 a in the centraldirection of the circle from the space part 13 a is the contact part 14where the split cores get in contact with each other when they are bent.In order to secure an accurate position of the two contact parts andincrease the bonding force, one of the contact parts has a contactprotrusion 14 a and the other one has a contact groove 14 b. When thesplit cores are bent, the contact protrusion 14 a and the contact groove14 b are coupled with each other. When the connection caulking part 15is formed after bending, preferably, the connection caulking part 15 isformed to cross the contact protrusion 14 a and the contact groove 14 bwhich are coupled with each other.

Referring to FIGS. 3 to 7, a method for manufacturing the laminated corefor the motor according to the present invention will be described.

FIG. 3 is a plan view showing one sheet 10 _(b1) of the core stamped inorder to manufacture the laminated core for motor according to thepreferred embodiment of the present invention.

As shown in FIG. 3, a thin steel sheet is stamped using a press deviceso as to form a sheet 10 _(b1) of a core like a form that a plurality ofsplit cores are connected in a row. The sheets of the core are laminatedperpendicularly to manufacture a laminated core, and in this instance,the number of the sheets of the core is m, and the number of the sheetsof the core is not limited.

FIG. 4 shows a state where a plurality of sheets 10 _(b1), 10 _(b2), . .. , and 10 _(bm) of the core stamped are laminated to manufacture thelaminated core for motor according to the preferred embodiment of thepresent invention. As shown in FIG. 4, each of m sheets of the core islaminated perpendicularly. After that, as shown in FIG. 5, the caulkingparts 110 and 120 are formed at the yoke part and the teeth part of eachsplit core. FIG. 5 shows a state where the caulking parts 110 and 120are formed after the sheets of the core are laminated to manufacture thelaminated core for motor according to the preferred embodiment of thepresent invention. Of course, the caulking parts 110 and 120 may beformed whenever each sheet of the core is stacked up. After the caulkingparts 110 and 120 are formed and all of the sheets of the core arestacked up, as shown in FIG. 6, the straight laminated core is bent tomanufacture a round laminated core. FIG. 6 shows a process to make theround laminated core 10 by bending the laminated core to manufacture thelaminated core for motor according to the preferred embodiment of thepresent invention.

After that, the connection caulking part 15 is formed at the contactpart 14 of each split core. Moreover, the connection caulking part 15 isalso formed at the part where the connection protrusion 11 a and theconnection groove 11 b formed at the contact parts of the first splitcore and the last split core are connected with each other. FIG. 7 showsa state where the connection caulking part 15 is formed on the roundlaminated core to manufacture the laminated core for motor according tothe preferred embodiment of the present invention.

While the present invention has been described with reference to theparticular illustrative embodiment, it is not to be restricted by theembodiment but only by the appended claims. It is to be appreciated thatthose skilled in the art can change or modify the embodiment withoutdeparting from the scope and spirit of the present invention.

What is claimed is:
 1. A laminated core for a motor manufactured bylaminating sheets of a plurality of cores, wherein the laminated core isformed by connection of a plurality of split cores, yoke parts of thesplit cores which are adjacent to each other get in contact with eachother so as to form a contact part, and a connection caulking part isformed at the contact part.
 2. The laminated core according to claim 1,wherein the contact part has a contact protrusion formed on one side anda contact groove formed on the other side.
 3. The laminated coreaccording to claim 2, wherein the connection caulking part crosses thecontact protrusion and the contact groove.
 4. The laminated coreaccording to claim 1, wherein the yoke has teeth, and each of the teethhas a straight line form on the end flat surface.
 5. A method formanufacturing a laminated core for a motor comprising the steps of:stamping a sheet of a core of a straight form to have a form that aplurality of split cores are connected; laminating sheets of the coreperpendicularly; bending the sheets of the core in a round form; andforming a connection caulking part at contact parts of yokes, which areadjacent to each other, of the bended core.